The present invention relates to a coffee machine in general and, in particular, to a coffee machine on which a given quantity of water inside a boiler is forced through ground coffee as a result of the overpressure formed inside the boiler when a heating source connected to the boiler is activated. The ground coffee is contained inside a filtering cup connected to a first outlet on the said boiler, a second outlet of which may be connected to an essentially-dry-steam supply nozzle.
On known coffee machines of the aforementioned type, activation of the boiler heating source results, after a given length of time, in practically all the water inside the boiler being forced through the ground coffee inside the filtering cup, and in the production of an equivalent amount of liquid coffee which is collected inside a vessel (possibly heatable) prior to being served in cups.
Known coffee machines of the aforementioned type involve a number of functional drawbacks, owing to the fact that practically all the water inside the boiler is fed through the coffee in one go, with no possibility of interrupting perculation other than by disconnecting the heating source.
As a result, the coffee is of inferior quality; a heated vessel is needed for collecting the left-over coffee; and practically no dry steam can be produced afterwards, as all the water in the boiler has been used up.